重要提示：为了使用 UCD SNMP 包，需要在编译之前将 NO_ZEROLENGTH_COMMUNITY 定义为 1。 在配置 UCD SNMP 之后，编辑 config.h 或 acconfig.h，查找 NO_ZEROLENGTH_COMMUNITY，将 #define 所在行的注释去掉。修改后应该类似这样：
#define NO_ZEROLENGTH_COMMUNITY 1
如果在组合 SNMP 命令时看到奇怪的字段错误，那就是因为没有遵从上述说明。如果不想重新编译 UCD SNMP，可以使用 --enable-ucd-snmp-hack 开关编译 PHP 以绕开上述错误。
Windows 版本在目录 mibs 中包含了支持 SNMP 的文件。此目录应该移到 DRIVE:\usr\mibs，其中 DRIVE 是安装 PHP 所在的盘符，例如 c:\usr\mibs。
There is no "mibs" directory in the php package, I check with 5.2,5.4,5.5 and 5.6, none of them has the net-snmp mibs folder.
What you have to do is download the source of net-snmap and copy the folder into your unpacked php folder besides the instructions provided above
net-snmap download link
https://sourceforge.net/projects/net-snmp/files/net-snmp/
after you download, unzip the file and copy folder mibs to your php folder
If net-snmp was not installed in default c:\usr folder (which may be the case for most peoples used to Windows instead of Linux), then, you should also create SNMP_PERSISTENT_DIR system environment variable with "persistent" folder location (located in snmp folder).
Otherwise, php will will create its own persistant folder in c:/usr/snmp/persistent folder, which is probably not what you want !
In order to build and install php in Ubuntu 12.10, beyond the normal "build-essential" package, I had to install the following packages: apache2-prefork-dev libxml2-dev libsnmp libsnmp-dev libtool
Command line should be like this:
sudo apt-get install apache2-prefork-dev libxml2-dev libsnmp libsnmp-dev libtool
If PHP complains that some mibs are missing and they are not included in your windows php package, they can be obtained from the source package of net-snmp itself.
For win32 (tested on win XP and 2k3 server 32bit):
Tested with versions 5.3.3 VC9, and 5.3.6 VC9.
The php_snmp.dll, requires that you set the environment variable MIBDIRS pointed to your MIBs folder.